Method of casting



Jan. 3, 1939.

A. G. E. ROBIETTE METHOD OF GAS TING Filed Nov. 25, 1936 Patented Jan.3,. 1939 UNITED STATES METHOD OF CASTING Alfred Gordon Evans Robiette,Erdington, Birmingham, England, assignor to The International NickelCompany, Inc., New York, N. Y., a corporation of Delaware ApplicationNovember 23, 1936, Serial No. 112,313 In Great Britain November 26, 19356 Claims.

In the production ofingots and other castings, the usual procedure is tocharge the-metal into a receptacle that is built. into or installed in amelting furnace and to pour the molten metal from the said receptacleinto open moulds. In

the working of this method. however, it is extremely difiicult, or evenimpossible, to avoid oxidizing contact between the metal and atmosphericair during the melting, pouring and cooling operations, so that oxygenor oxides become included in thecastings, with consequentdeteriorationof their physical properties.

The present invention purposes to eliminate the disadvantages thatattend the ordinary methods of melting and casting, and to provide forthe metal and casting of metal in mobile containers whilst the latterare passing successively and at a uniform speed through a furnace fromwhich atmospheric air is excluded.

According to the'said invention, it is proposed to charge the metal tobe melted and cast into a container which is fitted to and above the topof a mould and to pass the combined container-andmould unit through aheating chamber and a cooling chamber of a furnace of thecontinuoustype, the metal being melted whilst the combined unit is in the heatingchamber so that it can percolate into the mould in which it issolidified into ingot or other form whilst the unit is passing throughthe cooling chamber.

Referring to the drawing herewith submitted, and which illustratesdiagrammatically apparatus inaccordance with the invention:

Figure 1 is a sectional elevation of a furnace and Figure 2 is asectional elevation of a combined container-and-mould unit, thecontainer being shown charged with metal.

In the' said drawing, the metal is charged into a container or crucibleA which is socketed into the .mouth of a'mould B to form a mobilecontainer-and-mould unit, the container being provided with a perforatedfloor, or otherwise so constructed that, as 'the metal melts, itrmayper- ,colate or pass freely from the said container into the said mould.A plurality of charged units are mechanically conveyed in successioninto and through the heating chamber'C of a continuous type furnace bymeans ofap'ushe'r mechanism as each unit emerges from the said heatingcham-,

ber C it passes directly into andthrough the cool ing chamber D. Each ofthe units is passed through the furnace'in a definite controlled timeperiod and the rate 'of travel is such that the whole of the charge ineach container A is melted and run into the complementary mould B beforethe unit is discharged from the heating chamber C. whereas the moltenmetal is cooled to below its M or by placing them upon-a conveyor belt,and

oxidizing temperature before the unit is dis- I charged from the coolingchamber D.

The cooling chamber D is surrounded by a jacket through which water,air, or other cooling media flows from an inlet E to an outlet F,although, if desired, the jacket may be disposed on the underside onlyof the said chamber. Hence, as each unit passes into the coolingchamber, the mould is cooled by direct contact with the cooled floor ofthe chamber and the cooling of the molten metal takes place mainly fromthe bottom of the 'mould to the top so that the resulting casting is ofuniform metallurgical structure and the possibility of gas being trappedtherein is reduced to a minimum.

After each container-and-mould is discharged from the'cooling chamber,the mould is disconnected from the container to enable removal of thecasting.

The furnace is illustrated as a resistance type electric furnace havingresistance units H suitably connected to a source of electrical energy,but any appropriate type of furnace may be used, as will be clear tothose skilled in the art. In order to facilitate the movement throughthe furnace of the units, separated by spacers J, rails K may beprovided which extend from a position in advance of the charging openinginto the furnace and beyond a discharge opening at the end of thecooling chamber D. The melting and cooling being preferably carried outwith the exclusion of atmospheric air, doors L are provided for closingthe charging and discharging openings except when inserting or removingone of the units. Two doors may be provided, as shown at the chargingend of the furnace in Figure 1, at a distance from each other slightlyin excess of the length of a unit so as to form an air lock, and preventappreciable influx of air into or efliux of gas from the heating chamberC during a charging operation. The same arrangement may be used at thedischarge end. Any desired gaseous atmosphere may be obtained by flowingthe necessary ingredients into the heating chamber C through a conduit Gin the insulated wall I of the furnace from any suitable source ofsupply.

Preferably the heating chamber of the furnace is maintained at atemperature above the melting point of the metal so that after thecontainer charge has been melted and run into the matrix of the mould,the casting is maintained in a molten condition up to the time of itsconveyance into the cooling chamber. Or, if required, the

casting may be subjected to super-heating by passing the same through azone of the furnace wherein the temperature is higher than that reitbecomes a comparatively simple matter to exclude air from the moltenmetal and thus protect ness in the finished casting.

Alternatively, in cases where the prevention of oxidation is notessential, and/or where it is desired to impart special characteristicsto the metal during the melting and/or casting operations, the saidoperations may be conducted in a fur nace which is charged with a gaswhich will react with the molten metal and impart the desiredcharacteristics thereto. A

Having described my invention, what I claim and desire to secure byLetters Patent is:

l. A'method or process of melting and casting metals in which metal ischarged intoa container fitted to and above the top of a mould to form acombined container-and-mould unit, the said unit is passed through aheating chamber of a furnace where the whole of the metal to be cast ismelted and passes into said mould, and said unit is then passed directlyinto and through a cooling chamber of said furnace'where the-metal issolidified; the heating and cooling operations being carried out withthe exclusion of atmospheric air.

2. A method or process of melting and casting metals according to claim1, in which the heating and cooling operations are carried out in areducinE' K88 and the cast metal is cooled to below its oxidizingtemperature before it is discharged from thecooling chamber. 3. A methodof melting and casting metals in a combined unit having a container witha permrated bottom cooperatively mounted on a mould and proportioned tohold about sufhcient metal to fill the mould entirely throughout itscross section and up to a region just below the perforated bottom ofsaid container which comprises placing a charge of metal to be melted onthe perforated. bottom of the container of. the aforesaid combined unit,subjecting said charged unit to a temperature higher than the meltingpoint of the metal in the container, maintaining said charged-unit at atemperature higher than the melting point of said metal for a period oftime suillcient to melt all of the aforesaid metal in the container andcause said'melted metal to flow into the mould t ereby filling thelatter throughout its cross section and up to a region just below theperforated bottom of said container, and cooling the molten metal insaid mould to solidify it whereby a sound casting can be producedunii'ormiy and successively.

4. A method of melting and casting metals in a plurality of combinedunitsadapted to move in succession through an environment comprising .aheating region and a cooling region, each unit having a container with aperforated bottom cooperatively mounted on a mould and proportioned Ito'hold about suflicfent metal to fill the mould entirely throughout itscross section and up to a container which comprises placing a charge ofmetal to be melted on the perforated bottom of each container of theaforesaid combined units. successively moving the charged units througha heating region while subjecting them to a temperature higher than themelting point of the metal in the containers, maintaining said chargedunits. at a temperature higher than the melting point of said metal fora period of time sufficient to melt all of the aforesaid metal in thecontainers and to cause said metal to flow into the complementarymoulds, maintaining the metal which and proportioned to hold aboutsuilicient metal to fill the mould entirely throughout its cross sectionand up to a region just below the perforated bottom of said containerwhich comprises placing a charge of-metal to be melted on the perforatedbottom of the container of the aforesaid combined unit, subjecting saidcharged unit to a tempera- -ture higher than the melting point of themetal in the container while excluding atmospheric air,

maintaining said charged unit while excluding stmospheric air at atemperature higher than the melting point 61' said metal for a period oftime sufllcient tomelt all of the aforesaid metal in the container andto cause said melted metal to flow into the mould-thereby filling thelatter throughout its cross section and up to a region just below theperforated bottom of said container, and

cooling the molten metal in said mould while excluding atmospheric airto solidify it whereby a casting substantially free from oxidation canbe produced uniformly and successively.

6. A method of melting and casting metals ina combined unit having acontainer with a perand proportioned to hold about suilicient metal toLfill the mould entirely throughout its cross section and up to a regionjust below the perforated bottom of said container which comprisesplacing forated bottom cooperatively mounted on a mould a charge ofmetal to be melted on the perforated bottom of the container of theaforesaid combined unit,- subjecting said charged unit in the presenceof a reducing gas to a temperature higher than the melting point ofthevmetal in the container, maintaining said charged unit in thepresence of a reducing gas at a temperature higher than the meltingpoint of said metal for a period of time suilicient to melt all of theaforesaid metal in the container and tocause said melted metal to flowinto the mould thereby filling the latter throughout its cross sectionand up to aregion just below the perforated bottom of said container,cooling at reducing gas to solidify it, and maintaining the cast metalin a reducing atmosphereuntii it has cooled below its oxidizingtemperature whereby castings-free from oxides can be produced uniformlyand successively.

ALr'aEn aonnou Evans RQBIET'I-E.

A the molten metal in said mould in the presence of

